Silicon carbide (SiC) exhibits many attractive electrical and thermophysical properties. Silicon carbide is especially useful due to its physical strength and high resistance to chemical attack. Silicon carbide also has excellent electronic properties, including radiation hardness, high breakdown field, a relatively wide band gap, high saturated electron drift velocity, high temperature operation, and absorption and emission of high energy photons in the blue, violet, and ultraviolet regions of the spectrum. Some of the properties of SiC make it suitable for the fabrication of high power density solid state devices.
SiC is often produced by a seeded sublimation growth process. In a typical silicon carbide growth technique, a substrate and a source material are both placed inside of a reaction crucible. A thermal gradient created when the crucible is heated encourages vapor phase movement of the materials from the source material to the substrate followed by condensation upon the substrate and resulting bulk crystal growth.
For many applications it is desirable that the crystal have high-electrical resistivity. It is known that impurities can be introduced as dopants into SiC and that these dopants can regulate certain properties including the electrical resistivity. If the SiC is produced in a sublimation growth process as discussed immediately above, a dopant can be introduced into the chamber in any of various ways so that the dopant will be present in the SiC crystal produced from that process. The process is controlled to provide an appropriate concentration of the dopant for a particular application.